(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
GN[168dx]PB[Black to play and capture some white stones]AW[kp][mp][np][lq][oq][pq][kr][or][qr][ks][ps][qs]AB[op][pp][rp][nq][qq][mr][rr][rs]
(;B[ms]C[This is the correct play.]
(;W[ns]C[This is White's strongest reply.]
;B[nr]
;W[mq]
;B[os]C[It leads to a yose ko (a one move approach ko).
White will probably lose all six stones.])
(;W[nr]C[White can instead play here to save four of the stones..]
(;B[ns]
;W[mq]
;B[os]C[White is short of liberties and loses three stones.])
(;B[mq]C[Clearly black should not play here as White makes two eyes.]
;W[ns]))
(;W[mq]
(;B[nr]C[Black should not play here either as it will be ko.]
;W[lr]
;B[os]
;W[ns])
(;B[ns]
;W[nr]
;B[os]C[Again White is short of liberties])))
(;B[nr]C[This play fails.]
;W[ms]
;B[ns]
;W[lr]
;B[ls]
;W[mq]C[Black never gets the chance to atari White.])
(;B[ns]C[Also this play fails.]
;W[ms]C[White has this tesuji to trash Black's shape.]
(;B[ls]
;W[nr]
(;B[ms]
;W[mq]
;B[os])
(;B[lr]
;W[mq]))
(;B[nr]
;W[lr]
;B[ls]
;W[mq])))
